Tough one 
. You are definitely accessing a card, but are you accessing it from R&D? It’s an R&D card alright, but you didn’t make a successful run on R&D. So possibly you are accessing from some sort of limbo? 
edit:
@hypomodern Actually this totally makes sense, I would be surprised if it was ruled the other way.
Shiro: “The Runner accesses the top card of R&D unless the Corp pays 1c.”
R&D Interface: “Whenever you access cards from R&D, access 1 additional card from R&D.”
I would think that it works like common sense says it does, and would be very surprised if it was ruled the other way, but it is technically worded differently from Raymond Flint: it’s not “access 1 card,” it’s “access the top card.” I still think it’s just semantics, but I could see an argument being made the opposite way.
For comparison:
Raymond Flint: “Whenever the Corp takes at least 1 bad publicity, access 1 card from HQ.”
HQ Interface: “Whenever you access cards from HQ, access 1 additional card from HQ.”)
Well, there is no “top card” of HQ, so that’s why I suspect the wording is the way it is… why I said it was “similar” :).
I feel like the biggest impact of planned assault won’t be more account siphons (although that’s certainly a factor), but easy access to indexing in criminal (multiple times too with same old thing), giving them the ability to put a big pressure on HQ AND R&D. That’s a game changer.
I asked this question on BBG and the answer most people agreed with that it /does/ combo - Shiro becomes a double edged sword - on one hand you may have to pay to prevent them from accesing 2 cards. On the other hand, you can force them into multiple Snares/Shocks whatever you want to force them into
That actually makes Shiro way more awesome at what it does 